This invention relates to a system for controlling the speed of a boat.
Motorboats typically include a throttle lever positioned in the cockpit and connected via a push-pull cable to the throttle of the motor. The word xe2x80x9cthrottlexe2x80x9d is intended to mean any device that controls the output of a motor. For example, in carbureted vehicles, the throttle controls the fuel and air intake into the motor; while in some fuel-injected vehicles, the throttle controls air intake.
Referring to FIG. 1, a boat 1A includes a motor 5A mounted to the stem of the boat and a throttle 7A for regulating the speed of the motor. Within the cockpit area of boat 1A is a throttle lever 10A, which is connected to throttle 7A via a push-pull cable 12A (e.g., Bowden cable). A shift mechanism connected to the boat""s transmission is generally incorporated within the throttle lever 10A as well. The position of the lever, therefore, is used to regulate the speed and usually the direction (i.e., forward or reverse) of the motor. In particular, to control the boat""s speed, the operator sets the lever at a predetermined position to drive the boat at a constant speed. To drive the boat in the forward direction, the operator pushes the lever forward from a center position; and to drive the boat in the reverse direction, the operator pulls the lever back from the center position.
Manually positioning the throttle lever 10A, however, does not ensure that the speed of the boat is constant. A number of other factors influence the actual speed of the boat including changing water conditions, e.g., from waves and from the boat xe2x80x9ccoming on or off plane.xe2x80x9d In other words, while the motor provides a constant power output for a predetermined hand lever position under stable conditions, the speed of the boat in actual conditions varies because the moving boat is experiencing other forces. Thus, to maintain a uniform speed, the operator is generally required to repeatedly adjust the position of the throttle lever.
The invention features a control system for controlling the speed of a boat of the type including a motor and throttle control lever.
In one aspect of the invention, the control system includes a position detector configured to detect the position of the throttle control lever and to generate a first signal representative of a target speed of the motor; a sensor which generates a second signal representative of the actual speed of the motor; an actuator adapted to control the throttle; and a servo controller, which in response to the first signal and the second signal, generates an output to adjust the position of the actuator.
Embodiments of this aspect of the invention may include one or more of the following features. The position detector and the throttle control lever are remotely located from the actuator. The positions of the input device are representative of a target speed of a motor of the boat. Alternatively, the positions of the input device are representative of a target speed of the boat. The control system further includes a manual override mechanism concentrically mounted and releasably coupled to the control system. A pin is provided for releasably coupling the manual override mechanism to the control system. A pin is provided for releasably coupling the manual override mechanism to the control system. {SWIxe2x80x94this paragraph talks about releasable shiftingxe2x80x94not my invention, and not included in the first implementation. I think this wording was intended to make the point about the original design. That design was to have a mechanical backup mechanism that allowed disabling of the actuator and enabling of the throttle lever to mechanically move the throttle in the event of a system failure
In another aspect of the invention, a method of controlling the speed of a boat includes the following steps. A position of an input device is detected and a first input based on the position of the input device is generated, the first input being representative of a target speed of a motor of the boat.
In another aspect of the invention, a control system includes a first servo control loop to control the speed of the boat and a second servo control loop to control the speed of the motor. The first servo control loop has input signals and an output signal while the second servo control loop also has input signals, one of which is the output signal from the first servo control loop.
The cascaded servo loops are employed to allow precise tuning of the servo operation for different aspects of the boat response, e.g.xe2x80x94the throttle actuator has a dedicated servo loop to tune its performance relative to precisely actuating the throttle mechanism. Motor speed is precisely controlled with an RPM servo loop. Furthermore, in another embodiment of the invention, the control system includes a third servo loop to allow tuning of the response to the dynamics of the boat and speed detection.
The method further includes detecting an actual speed of the motor, generating a second input representative of the actual speed of the motor, and generating an output, on the basis of the first input and the second input, to minimize the difference between the first input and the second input. Among other advantages, the control system provides for stable and predictable control of the speed of a boat. With this arrangement, the control system and its method of operation allows the operator to maintain the speed of the boat or motor without having to repeatedly adjust the hand lever. The control system can be interfaced to an existing standard boat control such that little or no training is required to learn the operation of the control system since the user interface is similar to standard controls. The control system can be used at all boat speeds, including very slow speeds. The control system can also be installed on standard locations on the boat without the need for much additional hardware mounting space. The cascaded loops allow fast servo loop response to maintain steady RPM control, while the slower boat speed control loop adjusts the desired RPM. This makes it possible to have quick response and a high degree of control.
Other features and advantages of the invention will be apparent from the description of the preferred embodiment thereof, and from the claims.